The Fusion is larger and heavier than a 15-gauge pneumatic nailer, but it has the same feel, especially the instant pop you get when you squeeze the trigger. It can be placed in an upright position so it’s easy to grab with either hand.

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When I heard that Senco was introducing a new cordless finish nailer, I was both excited and skeptical — excited because I dislike using hoses, and skeptical because as a long-time user of cordless finish guns I am aware of their shortcomings. This new gun is the first in a family of tools called Fusion, and Senco claims that it will do away with most of the problems associated with cordless guns.

For the last few months I have been using the 15-gauge model, the FN65DA. An 18-gauge Fusion, the FN55AZ, is scheduled to be released around the time this story is published, and Senco says that other models are in the works.

Cordless Technology
Before the Fusion was introduced, there were two kinds of cordless nailers, gas and electro-mechanical.

A gas nailer is powered by an internal combustion engine that burns liquefied petroleum gas; the force of the exploding fuel propels the driver into the head of the fastener. I have been using Paslode gas nailers for 10 years. They work well but have some issues: They consume fuel cells, emit smelly combustion gases, and require regular cleaning to function properly.

An electro-mechanical gun uses a battery-powered motor to spin a flywheel. When the carpenter presses the trigger, the flywheel transfers power to the driver, causing it to strike the nail. I've used the electro-mechanical finish guns from DeWalt and Senco, and they simply don't measure up to gas models. They work, but there's a delay while the flywheel comes up to speed — plus they're heavy, bulky, and poorly balanced.

A third way. The Fusion gun uses a battery-powered motor to compress nitrogen gas in a sealed cylinder by lifting a piston against it. Squeezing the trigger releases the piston, allowing the compressed gas to propel the driver into the nail — same as in a pneumatic tool. As soon as the nail is driven, the motor retracts the driver, which recompresses the nitrogen. The entire cycle takes a fraction of a second.

Using the Gun
According to Senco, the Fusion combines the power and feel of a pneumatic nailer with the convenience of a cordless tool. I agree: When you shoot this gun it has the instantaneous pop of a pneumatic nailer — but without the blast of air at the end of the cycle. The nitrogen is sealed inside the drive cylinder and gets used over and over, like the gas in an air-shock or door lifter. The tool is quieter than a gas nailer, but I still wear ear protection.

We used the Fusion to drive fasteners up to 2 1/2 inches long in plywood, poplar, cherry, MDF, pine, and Douglas fir framing material. There was no issue with power — it drove as well as our pneumatics.

The 15-gauge Fusion is very well-balanced, so even though it's heavier than a gas finish nailer, using it is not a hardship. A rubberized grip and body make the gun comfortable to hold and protect the surfaces it's placed on. Most nailers will only lie on their sides, but this one can be placed upright on the magazine, making it easy to grab and go.

Firing modes. The gun has a dry-fire lockout that prevents it from firing when empty and putting unnecessary holes in the material. A three-position switch on the side of the housing allows the user to turn the tool on or off and set it to single-shot or bump-fire mode. I use the single-shot mode for finish work; it forces me to be deliberate about fastener placement, so I don't overnail the trim. The only time I use bump-fire is for fastening blocking. The gun is capable of driving about one nail per second, which is more than enough speed for finish carpentry.

A three-position switch can be set to bump-fire, off, or single-shot mode. Leaving the tool on for long periods of time can deplete the battery, even if the gun isn't fired.

Battery. The 18-volt lithium-ion battery has excellent runtime — we can often work all day on a single charge. A gauge on the back of the battery shows the remaining charge; if it's running low we charge the battery during a break. It takes 45 minutes to fully charge and empty the battery, but only 15 minutes to get an 80 percent charge.

A gauge on the 18-volt battery indicates the remaining charge.

The Fusion drives nails until the battery is no longer able to lift the driver, at which point the tool won't fire. There is no stair-stepping as the battery runs down — it drives at full power or not at all. The first time this happened, we thought the gun was broken. We took off the magazine, saw that the driver had not retracted, and realized the battery was depleted. Since the battery can be charged hot, we threw it in the charger and within five minutes it was sufficiently charged to drive 30 more nails, which was enough to finish the job. According to the manufacturer, the battery can drive up to 600 nails per charge.

Features
The gun comes with a stiff wire belt hook that can be flipped to either side of the handle. Depth-of-drive is controlled by a thumb-wheel on the front of the housing. The setting shows up on an incremental scale further down the nose.

A scale below the thumb-wheel provides a quick visual reference for the depth-of-drive setting.

The aluminum magazine is held in place by a spring-loaded lever and can be quickly removed to ease the clearing of jammed fasteners. This is an improvement over existing cordless models, which can be difficult to unjam.

An LED light built into the front of the tool comes on whenever the trigger is squeezed or the contact element compressed.

When the trigger is squeezed or the contact element depressed, a light comes on in the nose. It provides just enough illumination to help in low-light conditions.

Durability. There's no way of knowing how long this tool will last, though it feels well-made. The manufacturer claims that the drive cylinder can cycle more than 100,000 times without losing so much nitrogen it can no longer set nails. If the cylinder fails, it can be replaced but not repaired.

The Bottom Line
I am completely impressed with the 15-gauge Fusion. Comfortable and convenient to use, it's the first cordless finish nailer that can match the power and performance of a pneumatic gun. It's more expensive than a gas finish nailer, but I would happily buy it anyway to avoid the smell of exhaust gas, the cost of fuel cells, and the hassle of regular cleanings.

Jesse Wright is a finish carpenter for Architectural Molding in Pleasant Hill, Calif.